<!{|style="float: left;"|{{Language-- table at top of page with logo, picture, Application level, Management level, and input-output tables -->box|english_link=Fossa_Alterna|french_link=Latrine_à_fosses_alternées_(Fossa_Alterna)|spanish_link=Fossa Alterna (Español)|hindi_link=coming soon|malayalam_link=coming soon|tamil_link=coming soon | korean_link=coming soon | chinese_link=Coming soon | indonesian_link=Coming soon | japanese_link=Coming soon}}|}{|width="100%"|style="width:50%;"|{{santablesantable_new|
sys1=[[Waterless System with Alternating Pits|2]] |
sys2=|
sys7=|
sys8=|
sys9=|
pic=Fossa_alterna.png|
ApplHousehold=XX|
ManShared=XX|
ManPublic=X|
Input1=Excreta|Input2=Faeces |Input3=Organics | Input4=Anal cleansing water| Input4= |Input5=Dry Cleansing Materials|Output1=Compost - EcoHumusPit Humus| Output2= | Output3= | Output4= | Output5=
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|[[Image:Fossa_alterna.png |right|500px]]
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[[Image:Icon_fossa_alterna.png |right|80px]]
'''The Fossa Alterna is a short cycle alternating, waterless (dry) double pit technology. Compared to the [[Double Ventilated Improved Pit | Double VIP]] (S.4) which is just designed to collect, store and partially treat excreta, the Fossa Alterna is designed to make an earth-like product that can be used as a nutrient-rich soil conditioner. The Fossa Alterna is dug to a maximum depth of 1.5 m and requires a constant input of cover material (soil, ash, and/or leaves).'''
'''The Fossa Alterna is an alternating, waterless (dry) double pit technology. Compared to the [[Double Ventilated Improved Pit|Double VIP]] which is just designed to collect, store and partially treat excreta, the Fossa Alterna is designed to make [[Sanitation Products#Compost - EcoHumus|EcoHumus]]. The Fossa Alterna is dug to a maximum depth of 1.5 m and requires a constant input of soil.'''
One of Cover material should be added to the Fossa Alterna pits should fill over pit after defecation (not urination). The soil and leaves introduce a period variety of 12–24 months depending on the size of the pit organisms like worms, fungi and bacteria which help in the number of usersdegradation process. The full pit degrades during Also, the period of time that the second pit pore space is fillingincreased, whichallows for aerobic conditions. Additionally, ideallyash helps to control flies, should take one year. The material in reduces odours and makes the full pit will degrade into a dry, earth-like mixture that can be easily removed manuallymix slightly more alkaline.
SoilThe full pit degrades while the second pit is filling, which, ashideally, and/or leaves should be added to take one year. The material in the full pit after defecation (not urination)will degrade into a dry, earth-like mixture that can be easily removed manually. The soil and leaves introduce a variety Because of organisms like wormsthe added carbon-rich bulking material, fungi and bacteria which help in the degradation process. Alsois accelerated, and the pore space content is increased, which allows ready for anaerobic conditions. Additionally, the ash helps to control flies, reduce odours excavation and make the mix slightly more alkalineuse much faster than in a Double VIP.
The [[Image:Fossa_alterna.PNG|thumb|right|200px|[[Fossa Alterna should be used for urinealterna |Fossa alterna]], but water should not be added in Epworth (small amounts of anal cleansing water can be tolerated). Water encourages the development of vectors and pathogens but it also fills the porespaces and deprives the aerobic bacteria of the oxygen that is required for degradation. The choice of User Interface will determine the material that enters the pit. Since bulking material is used to continuously cover the excretacredits, smells are reduced but click the addition of a ventilation pipe can reduce the smells even further.picture)]]
The ===Design Considerations=== A Fossa Alterna pits are relatively shallow with pit would fill over a depth period of 1.5m12 to 24 months depending on its size and the number of users. Even though the pits are shallow(1 to 1.5 m), this should each of them can be more than enough space to accommodate used by a family of 6 six for one year. To optimize the space, the material that mounds in the centre of the pit (underneath the toilet) should be pushed to the sides periodically. Unlike a simple or ventilated pit which The Fossa Alterna technology will be covered or emptied, only work properly if the material in the Fossa Alterna is meant to be reusedtwo pits are used sequentially and not concurrently. Therefore, it is extremely important that no garbage is put into an adequate cover for the out of service pit as it will reduce the quality of the material recovered, and may even make it unusableis required.
Emptying the The Fossa Alterna is easier than emptying other pits: should be used for urine, but water should not be added (small amounts of anal cleansing water can be tolerated). Water encourages the development of vectors and pathogens, but it also fills the pits are shallower pore spaces and deprives the addition aerobic bacteria of soil means the oxygen that the material is less compactrequired for degradation. A UDDT (U. The material that is removed 2) can be used with the Fossa Alterna, but only in circumstances when the soil cannot sufficiently absorb the urine or when the urine is not offensive and presents a reduced threat of contaminationhighly valued for application.
Since cover material is used to continuously cover the excreta, smells are reduced. To reduce the smells even further, a ventilation pipe can be added. In flood-prone areas and where the groundwater table is too high, the Fossa Alterna could be raised or built entirely above ground to avoid water intrusion and groundwater pollution. Raising the pits could also be an option for rocky ground and compacted soils that are difficult to dig. If space is abundant and emptying not desired, the [[Fill and Cover - Arborloo | Arborloo]] (D.1) can be an alternative Disposal option. Pits should not be lined if used as an Arborloo.
{{procontable | pro=
- Can be built and repaired with locally available materials. <br> - Because double pits are used alternately, their life is virtually unlimited. <br> - Excavation of humus is easier than faecal sludge <br> - Significant reduction in pathogens <br> - Generates nutrient- Potential rich humus with good potential for use of stored faecal material as soil conditioner. <br> - Flies and odours are significantly reduced (compared to non-ventilated pits). <br> - Does not require a constant source of water. Can be built and repaired with locally available materials <br> - Suitable for all types of user (sitters, squatters, washers and wipers). <br> - Low (but variable) capital costs depending on materials; no or low operating costs if self-emptied. <br> - Small land area required. <br> - Significant reduction in pathogens. | con=- Requires constant source of cover material (soil, ash, leaves, etc.) <br> - Manual removal of humus is required<br>- Garbage may ruin reuse end-use opportunities of Compost/EcoHumus. the product
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===Appropriateness===
The Fossa Alterna is appropriate for rural and peri-urban areas. It is especially suitable to water-scarce environments. It is a useful solution for areas that have poor soil and could benefit from the use of the stabilized humic material as a soil amendment. The Fossa Alterna is not appropriate for greywater as the pit is shallow and the conditions must remain aerobic for degradation. The material is manually emptied from the Fossa Alterna (it is dug out, not pumped out); thus, vacuum truck access to the pits is not necessary.
==Adequacy== The Fossa Alterna is not suited for rocky or compacted soils (that are difficult to dig) or for areas that flood frequently, except if the pits are raised.
The ===Health Aspects/Acceptance=== By covering faeces with soil, ash, and/or leaves, flies and odours are kept to a minimum. Users may not understand the difference between the Fossa Alterna is appropriate for rural and peri-urban areasa Double VIP, although if given the opportunity to use one, people should have a good appreciation of the advantages. It is especially adapted Demonstration units can be used to waterscarce environments. It is show how easily one can empty a useful solution for areas that have poor soil and could benefit from the composted humic material as Fossa Alterna in comparison to emptying a soil amendment. A constant source of soil, ash and/or leaves is requireddouble pit.
The Fossa Alterna is not appropriate Keeping the contents sealed in the pit for greywater as the pit is shallow duration of at least one year makes the material safer and the conditions must remain aerobic for degradationeasier to handle. Another greywater treatment system must be used in parallel. A [[Urine Diverting Dry Toilet]] can The same precautions that are taken when handling compost should be used taken with the humus derived from the Fossa Alterna, but only in circumstances when the soil cannot sufficiently absorb the urine or when urine is highly valued for application.
The material is manually emptied from ===Operation & Maintenance=== When the Fossa Alterna (it first pit is dug output into use, not pumped out)a layer of leaves should be put onto the bottom of the pit. Periodically, so vacuum truck access more leaves should be added to increase the pits is not necessaryporosity and oxygen availability. The Fossa Alterna technology will only work properly if Following the two pits are used sequentially addition of faeces to the pit, a small amount of soil, ash, and not concurrently/or leaves should be added. ThereforeOccasionally, an adequate cover for the out mounded material beneath the toilet hole should be pushed to the sides of service the pit is required. The Fossa Alterna is especially appropriate when water is scarce. It is not suited for rocky or compacted soils (that are difficult in order to dig) or for areas that flood frequentlyoptimise the use of space.
Unlike a [[Single Pit | Single]] or [[Single Ventilated Improved Pit | Ventilated]] Pit (S.2, S.3) which will be covered or emptied, the material in the Fossa Alterna is meant to be used as a soil conditioner. Therefore, it is extremely important that no garbage is put into the pit. Emptying the Fossa Alterna is easier than emptying other pits; the pits are shallower and the addition of soil, ash, and/or leaves means that the contents are less compact. The material that is removed is not offensive and presents a reduced threat of contamination.
==Health Aspects/Acceptance== Depending on the dimensions of the pits, the contents should not be emptied more often than once a year.
By covering faeces with soil/ash, flies and odours are kept to a minimum===Field experiences===The following project(s) utilize fossa alterna. Users may not understand the difference between the Fossa Alterna and a <br>{|style="border: 2px solid #e0e0e0; width: 20%; text-align: justify; background-color: #e9f5fd;" cellpadding="2"|- style="vertical-align: top"|[[Double Ventilated Improved PitImage:akvorsr logo_lite.png|Double VIPcenter|60px|link=http://akvo.org/products/rsr/]], although if given the opportunity to use one, people should have a good appreciation of the advantages|- style="vertical-align: bottom"|[[Image:project 644.jpg |thumb|center|140px|<font size="2"><center>[http://rsr. Demonstration units can be used to show how easily one can empty a Fossa Alterna in comparison to emptying a Double Pitakvo. Keeping the contents sealed in the pit for the duration of at least one year makes the material safer and easy to handleorg/project/644/ RSR Project 644]<br>Rwenzori Integrated School WASH Project</center></font>|link=http://rsr. The same precautions that are taken when handling compost should be taken with the humus derived from the Fossa Alternaakvo.org/project/644/ ]] |}
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===Manuals, videos, and links===
This [https://sswm.info/taxonomy/term/3916/fossa-alterna document] contains a lot of information about building, maintaining a fossa alterna.
==Maintenance=References and external links===
When the first pit is put into use* Morgan, a layer of leaves should be put into the bottom of the pitP. Periodically, more leaves should be added to increase the porosity and oxygen availabilityR. (2007). [http://www.ecosanres. Following the addition of faeces to the pit, a small amount of soil or ash should be addedorg/pdf_files/ToiletsThatMakeCompost. To lengthen the filling time of the pit soil is not added to the pit following urinationpdf Toilets That Make Compost.OccasionallyLow-Cost, the mounded material beneath the toilet hole should be pushed to the sides of the pit Sanitary Toilets That Produce Valuable Compost for Crops in an even distribution of materialsAfrican Context]. Depending on the dimensions of the pitsStockholm Environment Institute, Stockholm, materials should be emptied every yearSE.
* Morgan, P. R. (2009). [http://www.ecosanres.org/pdf_files/EcologicalToilets-PeterMorgan-Mar2009.pdf Ecological Toilets. Start Simple and Upgrade from Arborloo to VIP]. Stockholm Environment Institute, Stockholm, SE.
==References=Acknowledgements===* Elizabeth Tilley et.al (2008). [http{{://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_high.pdf Compendium of Acknowledgements Sanitation Systems and Technologies] ([http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_low.pdf low res version]). Department of Water and Sanitation in Development Countries ([http://www.sandec.ch/ Sandec]) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). (Provides a full overview of sanitation systems.) * Morgan, P. (2007) Toilets That Make Compost: Low-cost, sanitary toilets that produce valuable compost for crops in an African context. Stockholm Environment Institute, Sweden. Available: http://www.ecosanres.org (Step-by-step guide for building a Fossa Alterna.)}}